Tube bending apparatus



e. E. FRANCK 2,702,065

TUBE BENDING APPARATUS Feb. 15, 1955 Filed Sept. 14, 1950 2 Sheets-Sheet 1 INVEN TOR.

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United States Patent TUBE BENDING APPARATUS George E. Franck, Riverside, [1]., nssignor to The Im- Bigass Manufacturing Company, a corporation 0 0 Application September 14, 1950, Serial No. 184,764

2 Claims. (Cl. 153-40) This invention relates to a tool and more particularly to a tube bending tool.

It is the general object of this invention to produce an improved tube bending tool.

It is a more specific object of this invention to produce a tube bending tool which is economical to manufacture and which is eificient in operation.

Yet another object of the invention is to produce a tube bending tool which is adapted to bend tubes of various diameters.

A further object of the invention is to produce a tool of the type described in the preceding paragraph which is adapted to operate with a number of interchangeable mandrels and is provided with a plurality of shoes, one being cooperable with each of the mandrels to bend tubes of various diameters.

Other and further objectives of the invention will be apparent from the following description and drawings, in which:

Figure 1 is a top plan view of one form of tube bending tool of this invention;

Figure 2 is a side elevation of the tool shown in F1g-, ure 1;

Figure 3 is a section along line 3-3 of Figure 1;

Figure 4 is a side elevation of the left hand portion of Figure 1;

Figure 5 is a view like Figure 1 of a modified form of the invention;

Figures 6 and 7 are sections taken along lmes 6-6 and 77 respectively, of Figure 5; and

Figure 8 is a plan view of an interchangeable mandrel for use with the tool of Figure 5.

While the invention is described in its preferred embodiments, it is to be understood that the description is exemplary in nature and should not be taken as limiting the invention to the specific embodiments described. The scope of the invention will be pointed out in the appended claims.

Referring now to Figures 1 to 4 of the drawings, the tool comprises a base 10 provided with an integral ear portion 11. A pinion 12 is rotatably mounted on the ear 11 and is provided with a shaft portion 12a having a handle 13 extending therethrough for rotating the pinion. The shaft portion has a squared upper end 14 to WhlCh a wrench may be secured for rotating the pinion should the force required exceed that which may conveniently be applied with the handle. A spur gear 15 is rotatably mounted upon a shaft 16 secured to the base 10 and meshes with the pinion 12. The gear 12 is provided with teeth about its entire circumference, that is throughout 360 of its circumference. Fixed to the gear 15 by the screws 17 and lying in a plane parallel to, but laterally spaced from the gear is a mandrel 18 provided with a circumferential groove 19 adapted to receive a tube. The groove extends completely around the mandrel except adjacent the location of a screw 21 secured to a flattened portion 21a of the mandrel. Pivotally mounted on the screw 21 is'a hook which is provided with a sharpened leading edge 22 adapted to engage a tube 23 positioned in the groove 19. The leading edge 22 is sharpened so as to prevent slippage between the hook and tube and to draw the tube around the mandrel with rotation of the mandrel.

The base is provided with a second integral ear portion 24 in which is rotatably mounted a shaft 25 which carries a disc 26 at one end. Mounted eccentrically of the center of the disc is a shaft 27 which carries a shoe 2,702,065 Patented Feb. 15, 1955 28, rotatably mounted thereon, and means in the form of a handle 29 secured to the shaft 27 is provided to rotate the shaft. The shoe is provided with a hemi-cylindrical groove 29a adapted to match the groove 19 in the mandrel.

The eccentricity of the shaft 27 is such as to provide a space between the edges of the grooves in the shoe and in the mandrel to permit the insertion of the tube 23 laterally therebeteween. Thus, when the shaft 27 is rotated so as to move the shoe as far as possible away from the mandrel, the space between the edges of the shoe and the mandrel is at least just slightly greater than the diameter; of the tube. When the handle 29 is moved to the position shown in Figure 1, the edges of the groove in the shoe contact the edges of the groove in the mandrel to form therewith a circular tube receiving opening 30. In swinging the handle to the position shown in Figure 1, the disc 26 is rotated until a stop pin 31 carried by the shaft 25 strikes a shoulder 32 formed in the base 10. At this point the shaft 27 has been carried past the center line joining the axes of rotation of the disc 26 and the mandrel 18 and thus the shaft 27 is locked against rotation in a counterclockwise direction (as seen in Figure 1) under any radially outward force against the shoe and locked against rotation in a clockwise direction under the drag of a tube being bent by the pin 31 hearing against the shoulder 32.

As will be noted from an inspection of Figure ,1, the edges of the groove in the shoe are substantially tangent to the mandrel, with the opening 30 being located at the point of tangency, and extend away from the opening 30 on both sides of the point of tangency. The shoe is provided with an index mark 33 adapted to be matched with index marks 34 on the mandrel, the latter marks being spaced apart in order that the amount of bend imparted to the tube 23 may accurately be gauged. While.

the shoe extends away in both directions from the point of tangency of the edges of the groove with the mandrel (which point, as seen in Fig. l, is located approximately at the index mark 33), it will be noted that the shoe extends a much greater distance from the point of tangency in the direction opposite to the direction of movement of the tube during the bending operation; thus,

it extends away a greater distance from the entrance side of the opening 30 than from the exit side of the opening. It will also be noted that the point of tangency is offset from a line joining the axes of rotation of the mandrel and shoe, the offset being in a direction toward the exit side of the opening 30.

The bottom of the base 10 is provided with an arcuate cut away portion 35 adapted to receive a handle, if desired, or the entire base may be clamped in a vice, securely to hold the tool during the bending operation.

With a tube positioned in the opening, the hook 20 may be swung upwardly about its pivot point to engage the tube as shown in Figure 1. Rotation of the handle 13 serves to swing the hook and tube in a counterclockwise direction as shown in that figure to bend the tube. As a tube is being bent, the shoe is rocked on the shaft 27 to the position shown in Figure 1; that is the force of bending the tube causes the shoe to rock in the same direction that the mandrel is rotated, i. e. counterclockwise, thus forcing the edges of the groove in the shoe into firm contact with the edges of the groove in the mandrel. When this occurs the tube is, in effect, subjected to a drawing operation as it is pulled through the opening, and as the opening 30 locates the point of maximum bending force the drawing effect eliminates the possibility of flattening or creasing the tube during the bending operation. Rotation of the handle 13 may be continued until the tube reaches the position shown in the dotted lines of Figure l, at which point a bend will have been imparted thereto. If a greater bend is desired, rotation may continue beyond this point while if a lesser degree of bend is desired rotation may be halted before the 180 position.

It is clear from the foregoing that the embodiment just described may be provided with a shoe 28 and a mandrel 18 of dimensions adapted to receive and bend a tube of a certain predetermined diameter. In orderto provide a tool which is adapted to bend tubes of various diameters, the embodiment shown in Figures to 8 may be employed. 5

Referring to those figures, there is shown a base 40 provided with an integral ear portion 41; on which a pinion 42 is" rotatably mounted. Rotation of the pinion may bey'achieved by means of a handle 44. Meshing with the pinion 42 is a gear 45 rotatably mounted on a shaft 46 carried by the base 40. The gear 45 is provided with a slot 47 adapted to receive a key 48 integral with a mandrel 49. A sleeve 50 surrounds the shaft 46 and is held in place on the shaft by a split ring 50a seated in an annular groove in the shaft. The Sleeve is provided with external threads at its upper end adapted to engage the threads., of a cap member 51. It is contemplated that mandrels 49 of various sizes maybe used and ready interchangeability is achieved bv the construction just described. Thus, to change the mandrel, it is merely necessary to remove the cap 51 whereuponhthe mandrel 49 may be slipped off and a second mandrel of different diameter (such as the mandrel 49a shown in Figure 8) and provided with a tube-receiving groove of different diameter may he slipped on in its place. Each of the mandrels designed for use with the tool may be provided with integral key portions 48 adapted to key into the slot 47 in the gear, and each of the mandrels is provided with a hook 55 adapted to engage a tube positioned in the groove 52 as previously described.

Rotatably mounted in a second integral ear portion 56 is a shaft 57 which carries a disc 58. Mounted eccentrically of the center of the disc 58 is a shaft 59 to which a carrier 60 is swingably secured. A plurality of shoe portions 61 are provided about the periphery of the carrier 60, with each of the shoe portions being provided with a hemi-cylindrical groove 62. Suitable markings are carried by each shoe as well as each mandrel in order that the proper shoemay be matched with its corresponding mandrel.

Each of the shoes 61 is so located on the carrier as, when rotated to operative position, to have its groove so match the groove in its corresponding mandrel as to form a circular tube-bending Opening. similar to the opening 30 previously described. Furthermore, the shoes 1 mustnot only be located at various distances from the/shaft 59 to allow for the differences in the diameter of the mandrels employed but also, the shoes are so located about the periphery of the carrier as not to interfere with tube-bending operations when in inoperative position. To this end, the shoe for the 16 inch tube 18 2.143 inches from the center of the shaft 59, the shoe for the inch tube is 2.615 inches, that for the inch tube is 0.821 inch, and that for the inch tube is 1.625 inches, respectively from the center of shaft 59. In addition, the shoes are not equally spaced around the carrier 60, the inch, inch and inch shoes being respectively 63, 157, and 275 (clockwise) from the 36 inch shoe, and the length of each shoe is progressively smaller as the radius of the groove therein is smaller. Thus, the inch shoe is 2%,, inches long, the Vs inch is 2 inches long, the 86 inch is 1 inches long and the inch is 1% inches long.

As in the preceding embodiment, the eccentrically mounted shaft is provided with a handle 63 adapted to move the shaft in an arcuate path to separate the shoe and mandrel a distance at least slightly greater than the diameter of the tube for which they were designed, and, when rotated in the opposite direction, to bring the edges of the grooves in the mandrel and shoe together to form a tube bending opening. Again, as in the previous embodiment, when the handle is moved to the position shown in Figure 5, the shaft 59 is past dead center, that is, beyond a line joining the axes of rotation of the mandrel 49 and the disc 58. Also, when any shoe 61 is in operative position, such as that occupied by the inch shoe shown in Figure 5, the shoe has a portion extending away from the point of tangency with the mandrel on either side of the tube-bending opening formed by the shoe and mandrel at that point. Rotation of the shaft 59 during tube bending operations is prohibited by a pm 65 provided in the shaft 57 and adapted to bear against a portion of the base in the same manner as the pin 31 in the previously described embodiment.

If desired, a handle 66 may be secured to the base 40, or the base may be clamped in a vice, more firmly to gnp the base during the bending operation.

I cla1m:

1. In a tube bending tool having a base, a pinion rotatably mounted on the base, means for rotating the pinion, a gear meshing with the pinion and rotatably mounted on the base, and an interchangeable circular mandrel adapted tobe secured to the gear and having a circumferential groove, means for holding any one of a plurality of tubes of different diameters in a matchmg groove in a mandrel comprising: a shaft rotatably mounted on the base and having a member eccentrically mounted on the shaft, a shoe carrier rotatable on said eccentrically mounted member, said carrier being shaped to carry shoe portions on its periphery at spaced apart positions, said carrier being rotatable on said shaft to move one shoe portion into tangent contact with one mandrel and slmultaneously move the other shoe portrons to a position out of the way and spaced from the extended l1ne of the groove in the contacting shoe portion and mandrel, handle means secured to said eccentrically mounted shaft member for rotating the shaft in one direction to bring the edges of the groove in said contacting shoe portion against the edges of the groove in said last mentioned mandrel to form a circular tube bending opening and for rotating the shaft in the other d11'Ct1OI1 tO separate said edges a distance at least equal to the diameter of said tube bending opening for removing the tube, and means rotated with the gear for engaging a tube positioned in the opening.

2. In a tube bending tool having a base, a pinion rotatably mounted on the base, means for rotating the prmon, a gear meshing with the pinion and rotatably mounted on the base, and an interchangeable circular mandrel adapted to be secured to the gear and having a circumferential groove, means for holding any one of a plurality of tubes of different diameters in a matching groove in a mandrel comprising: a shaft rotatably mounted on the base and having a member eccentrically mounted on the shaft, a shoe carrier rotatably carried on said eccentrically mounted member, said carrier being shaped to carry shoe portions on its periphery at positions spaced apart distances of the order of 60, and 270 from one shoe portion to carry shoe portions of different size, said carrier being rotatable on said shaft to move one shoe portion into operative contact with one mandrel while moving the other shoe portions to an out of the way position on the axis of the carrier side of an extension of the groove in the contacting shoe portion and mandrel, handle means secured to said shaft member for rotating the shaft in one direction to bring the edges of the groove in said contacting shoe portion against the edges of the groove in said last mentioned mandrel to form a circular tube bending opening and for rotating the shaft in the other direction to separate said edges a distance at least equal to the diameter of said tube bending opening for removing the tube, and means rotated with the gear for engaging a tube positioned in the opening.

References Cited in the file of this patent UNITED STATES PATENTS 493,390 Stirling Mar. 14, 1893 559,839 Brinkman May 12, 1896 1,794,689 Holsclaw et al. Mar. 3, 1931 2,171,907 Beehler et al. Sept. 5, 1939 

